Something like this might be a start. I'm sure it could be optimized and included in is rather than a new function, but just to use fiddle, here is a newIs that can check objects and raw elements, then passes off to .is() for strings.
http://jsfiddle.net/timmywil/xWNJe/9/. However, I am using indexOf for an array and I don't think ie6 or ie7 support javascript 1.6. There may be something more clever to use, or a fallback should be written for those browsers.